What foods should you avoid while carb loading?

December 6, 2025 •

3 min read

Studies show that effective carbohydrate loading can boost endurance performance by up to 3%. To maximize these gains and prevent digestive issues on race day, it is crucial to understand what foods you should avoid while carb loading in the days leading up to your event.

Quick Summary

Athletes preparing for endurance events should prioritize easily digestible carbs and avoid high-fiber, high-fat, and overly processed foods to maximize glycogen stores and prevent stomach upset.

Key Points

Avoid High-Fiber Foods: Swap whole grains, beans, and high-fiber vegetables for refined versions like white rice and pasta to prevent bloating and GI issues.
Steer Clear of High-Fat Foods: Greasy and fried foods or heavy sauces slow digestion and can make you feel sluggish, hindering your ability to consume enough carbs.
Limit Excess Protein: While necessary for muscle repair, too much protein can be filling and compete with carbohydrates for absorption, so stick to lean, moderate portions.
Be Cautious with Spices and Caffeine: Spicy foods can irritate your digestive system, while excessive caffeine can lead to frequent restroom stops and discomfort.
Never Experiment with New Foods: Test your carb-loading strategy during training and stick to familiar, well-tolerated foods to avoid unexpected GI problems on race day.
Prioritize Hydration: Remember that glycogen stores with water. Drink plenty of fluids alongside your increased carb intake to stay hydrated and support the loading process.

The Core Principle: Less Fiber, Less Fat

Carb loading is a nutritional strategy employed by endurance athletes in the 1-3 days before an event lasting longer than 90 minutes. The goal is to maximize glycogen stores in the muscles and liver, providing a readily available fuel source to delay fatigue. Achieving this requires a dietary shift, not just eating more. The main principle is to focus on easily digestible, high-carbohydrate foods while significantly reducing intake of fiber, fat, and excess protein. These components slow down digestion and can cause unwelcome gastrointestinal (GI) issues on race day.

The Danger of High-Fiber Foods

High-fiber foods are great for daily health but can hinder carb loading by causing bloating, gas, and stomach upset due to their indigestibility. In the 24-48 hours before an event, swap high-fiber options like whole-grain bread and brown rice for low-fiber choices such as white bread and white rice.

Why High-Fat Foods Are Detrimental

High-fat foods are slow to digest and can make you feel full and sluggish, interfering with carbohydrate intake and potentially causing digestive discomfort during exercise. Avoid fried foods, creamy sauces, and fatty meats, focusing instead on lean, simple carbohydrates to optimize glycogen storage.

Foods and Ingredients to Strictly Avoid

During carb loading, limit or eliminate the following:

High-Fiber Vegetables: Avoid items like broccoli, beans, and lentils due to their potential to cause bloating and gas.
High-Fiber Fruits: Skip berries and apples with skin; choose lower-fiber fruits like bananas and melons or fruit juices instead.
Whole Grains: Replace whole-wheat products and brown rice with refined versions for easier digestion.
Fried and Greasy Foods: These high-fat options slow digestion and should be avoided.
Fatty Meats and Rich Dairy: High-fat protein and dairy sources are not ideal for carb loading.
Spicy Foods: Hot foods can irritate the digestive system.
Alcohol and Excessive Caffeine: Limit alcohol due to dehydration risks and caffeine to avoid stomach issues and frequent urination.
New or Unfamiliar Foods: Stick to tested foods to prevent unexpected digestive problems.

Comparison Table: Carb Loading Foods


Category	Foods to AVOID	Foods to EAT
Carbohydrates	Whole-wheat pasta, brown rice, oatmeal, bran flakes	White pasta, white rice, low-fiber cereal, pretzels, bagels
Fruits	Apples with skin, raspberries, fibrous fruits	Bananas, melons, canned fruit, 100% fruit juice, applesauce
Vegetables	Broccoli, beans, lentils, peas, artichokes	Peeled potatoes, sweet potatoes without skin, carrots
Proteins/Fats	Fatty meats (steak, sausage), heavy cream sauces	Small, lean portions of chicken, fish, or eggs
Beverages	Beer, wine, carbonated drinks, excess caffeine	Water, sports drinks, fruit juice

Practice Makes Perfect: Trialing Your Strategy

Experimenting with new foods just before a competition is not recommended. It is essential to test your carb-loading diet during training, particularly before long or intense sessions. This helps identify which foods are well-tolerated and the optimal amounts for fueling without discomfort. Many athletes find that consuming smaller, more frequent carbohydrate-rich meals throughout the day aids digestion. Testing your strategy builds confidence for race day.

The Role of Protein and Hydration

While carbohydrates are the focus, don't eliminate protein entirely. Include small, lean protein portions for muscle support, but keep intake moderate to prioritize carbs. Hydration is also vital; the body stores water with glycogen, so increasing fluid intake alongside carbs is necessary to prevent dehydration and cramps.

Conclusion: Fuel Smart, Race Strong

Effective carb loading is a strategic process, not an excuse for consuming unhealthy foods. Focus on easily digestible, low-fiber, and low-fat carbohydrates in the days leading up to an endurance event. Avoiding foods known to cause GI distress ensures optimal glycogen storage and performance. Always practice your fueling plan during training to be fully prepared and confident on race day.

For more expert advice on marathon preparation, consider reading A runner's guide to carb loading for a marathon.

Frequently Asked Questions

While high in nutrients, high-fiber foods like whole grains, beans, and certain vegetables are slow to digest and can cause unwanted gas, bloating, and stomach upset during a race. The goal is to fill your glycogen stores with easily absorbed carbohydrates.

High-fat foods, including fried dishes and creamy sauces, take longer to digest and can leave you feeling heavy and sluggish. They also displace the necessary carbohydrate intake, which is the primary fuel source for endurance events.

It is best to avoid alcohol during the carb-loading phase. Alcohol can dehydrate you and disrupt the body's ability to store glycogen effectively, negatively impacting your performance.

No, you don't need to cut out protein entirely. You should, however, moderate your intake and focus on lean protein sources in smaller portions. This ensures you still get benefits for muscle repair without competing with carbohydrate absorption.

No. While fruit is a great carb source, high-fiber fruits like berries and apples with skin can cause digestive issues. Stick to lower-fiber options like ripe bananas, melons, or fruit juice.

Yes, absolutely. Practicing your nutrition strategy, including your carb load, during your long training runs is crucial. This helps you determine which foods work best for your body and prevents any race-day surprises.

Weight gain during carb loading is normal and expected. For every gram of glycogen stored, your body also retains about 3 grams of water. This temporary water weight is a positive sign that your fuel tanks are full and ready for the event.